Evidence of chronic steatohepatitis, on liver biopsy done within the previous 12 months. Histologic criteria of steatohepatitis: diffuse, chronic liver disease characterized by (1) macrovesicular steatosis, (2) inflammation or evidence of hepatocellular drop-out, and (3) acinar zone 3 hepatocellular injury (ballooning degeneration). Additionally helpful, but not required, features include the presence of Mallory's hyalin and pericellular/sinusoidal fibrosis that predominantly involves zone 3.